docs/components/ThemeToggle.tsx

import { useTheme } from "next-themes";
import { type ComponentPropsWithoutRef, useEffect, useState } from "react";

function SunIcon(props: ComponentPropsWithoutRef<"svg">) {
    return (
        <svg viewBox="0 0 20 20" fill="none" aria-hidden="true" {...props}>
            <path d="M12.5 10a2.5 2.5 0 1 1-5 0 2.5 2.5 0 0 1 5 0Z" />
            <path
                strokeLinecap="round"
                d="M10 5.5v-1M13.182 6.818l.707-.707M14.5 10h1M13.182 13.182l.707.707M10 15.5v-1M6.11 13.889l.708-.707M4.5 10h1M6.11 6.111l.708.707"
            />
        </svg>
    );
}

function MoonIcon(props: ComponentPropsWithoutRef<"svg">) {
    return (
        <svg viewBox="0 0 20 20" fill="none" aria-hidden="true" {...props}>
            <path d="M15.224 11.724a5.5 5.5 0 0 1-6.949-6.949 5.5 5.5 0 1 0 6.949 6.949Z" />
        </svg>
    );
}

export function ThemeToggle() {
    const { resolvedTheme, setTheme } = useTheme();
    const otherTheme = resolvedTheme === "dark" ? "light" : "dark";
    const [mounted, setMounted] = useState(false);

    useEffect(() => {
        setMounted(true);
    }, []);

    return (
        <button
            type="button"
            className="flex h-6 w-6 items-center justify-center rounded-md transition hover:bg-zinc-900/5 dark:hover:bg-white/5"
            aria-label={
                mounted ? `Switch to ${otherTheme} theme` : "Toggle theme"
            }
            onClick={() => setTheme(otherTheme)}
        >
            <SunIcon className="h-5 w-5 stroke-zinc-900 dark:hidden" />
            <MoonIcon className="hidden h-5 w-5 stroke-white dark:block" />
        </button>
    );
}